Methods and circuits for measuring the thermal resistance of a packaged IC

Abstract

Disclosed is a DC thermal energy generator for heating localized regions of an integrated circuit. The integrated circuit includes a pair of static circuits whose outputs are shorted, and are in contention. Contention causes current to flow through the circuits, generating heat. Integrated-circuit temperature can be varied by turning on more or fewer thermal energy generators. The thermal resistance of a packaged integrated circuit is computed using a well-known relationship among the integrated circuit's measured temperature, power consumption, and the ambient temperature.

1. A method of determining thermal resistance of a packaged programmable logic device, wherein the packaged programmable logic device includes a package enclosing a programmable logic device on a die, the programmable logic device having a temperature sensor, configurable logic elements, and configurable interconnect lines, the method comprising:
 providing a set of the configurable logic elements and configurable interconnect lines in the programmable logic device; 
 configuring a configurable interconnect line of an electrical conduction path between an output terminal of a first gate and an output terminal of a second gate to form at least one DC thermal energy generator; and 
 determining and storing a thermal resistance of the packaged programmable logic device after applying a signal to the DC thermal energy generator. 
 
   
   
     2. The method of  claim 1 , further comprising:
 powering the DC thermal energy generator to heat the programmable logic device to a temperature; and 
 measuring the temperature. 
 
   
   
     3. The method of  claim 1 , further comprising:
 programming the configurable logic elements to instantiate the first gate. 
 
   
   
     4. The method of  claim 1 , further comprising:
 programming the programmable logic device to include a plurality of the DC thermal energy generators distributed across the programmable logic device; 
 powering up the programmable logic device, including the DC thermal energy generators; 
 allowing the programmable logic device to reach a temperature; 
 determining power consumed by the programmable logic device at the temperature. 
 
   
   
     5. The method of  claim 4 , wherein powering up the programmable logic device includes providing specified voltage to the programmable logic device. 
   
   
     6. The method of  claim 1 , further comprising varying the temperature by programming the programmable logic device to include a different number of the at least one DC thermal energy generator. 
   
   
     7. The method of  claim 1 , further comprising measuring the temperature of the programmable logic device by measuring a voltage drop across a temperature-sensing diode, and relating the voltage drop to temperature, based on a known relationship.